Well, it turns out that he should know, given the fact that he's sung it in Spanish himself on numerous occasions while stumping for votes!
As documented years ago in the book American Dynasty:
"When visiting cities like Chicago, Milwaukee, or Philadelphia, in pivotal states, he would drop in at Hispanic festivals and parties, sometimes joining in singing "The Star-Spangled Banner" in Spanish, sometimes partying with a "Viva Bush" mariachi band flown in from Texas.
But hey, why take the word of some non-credible li-buh-rul writer? Let's bring a credible news source into this discussion... like FoxNews, for instance!
"Expenses ranging from TV ads to a mariachi band pushed President Bush's re-election spending to $126 million last month..."